Spark plug



April 15, 1929- 'H. SCHLAICH 1,

I SPARK PLUG Filed May 1926 HER/Mm 56%4/1/0/ I Maw-M ATTORNEYS Patented Apr. 16, 1929.

warren sures HERMAN serrLAIcH, or LONG ISLAND orrr, NEW Yonn.

SPARK PLUG.

Application filed May 6,

The present invention relates to spark plugs. The principal object of the invention is to provide a spark plug which shall be thoroughly gas tight under operating conditions. Other objects and advantages will be pointed out hereinafter;

My invention will be best understood by reference to the following detailed description and to the accompanying drawings, in which Figure l is a view, partially in section, of an illustrative embodiment, together with portions of the tools used in assembling same; Figure? is a view in elevation of the device shown in Figure 1; Figure-3 is a plan View of the device shown in Figures land 2; Figure 4 is a View partly in section of a modification; and Figure 5 is a view in elevation of the device shown in Figure l.

Referring now to the drawings by characters of reference: denotes the insulating body or porcelain of the spark plug formed with an expanded intermediate portion, thus forming shoulders 11 and 12. Porcelain 1Q contains the usual electrode 13 and binding post 13. A shell is provided for said porcelain comprising a lower member A, having the usual depending threaded portion 16, a flange 17 above said threaded portion and a hexagonal portion 18 for receiving a wrench or the like. Member A, it will be noted, is provided with an internal shoulder 20 to cooperate with shoulder 12 of the porcelain, and to receive ther-ebetween packing 21. Member A is also provided with an annular upstanding portion 28 extending preferably almost to the upper shoulder 11 of the porcelain, which portion is provided with a lip 24;.

Cooperating with member A of the shell is an upper member B preferably of spring material, the upper edge of said member conforming with and bearing upon shoulder 11 of the porcelain. Member B as shown is preferably formed with an excess of mate- 'ial which is disposed so as to aid its spring function. As shown in Figure 1, this excess material is partially contained in an annular bowed-in portion 0.

The foregoing embodiment is preferably assembled as follows:

The parts comprising the porcelain 10 and the shell members A and B (the last named member then being capable of being slipped over lip 24) are held together under considerable pressure by means of an annular member 26, engaging the shoulder formed by the bowed-in portion 0, and supporting member Serial No. 107,005.

27 engaging the expanded portion 18 of a member A. a suitable mechanism, not shown, the lowermost portion of member Bis turned in beneath lip 2 1 by means of a rolling-in tool 2%). When this has been done, the spark'plug is removed from the clamping members and QTwhercupon the spring member 13 will continue to exert a force upon the upper shoulder 11 of the porcelain, pressing the latter down upon the packing 21 above the shoulder 20 of the lower member A.

It will be evident that the porcelain will be held tightly between the two cooperating shell members, and that such tension will be maintained throughout an extended tempera ture range, sutiicient to take care of all operating conditions. The reason that consir erable dii'liculty has heretofore been encountered in making spark plugs gas tight is due to the fact that the porcelain has a less coeflicient of expansion than the containing metal shell, so that when the former expands a slight space is left between the porcelain and the shell. By means of my invention, however, the upper shell member presses against the porcelain at all times, in spite of any differential expansion, and thus produces a thoroughly gas tight device.

It will also be noted that the upstanding portion 23 of member A affords a support for the porcelain 10 and furthermore prevents the material of member B at the bowed-in portion 0 from being forced into contact therewith.

In Figures l and 5 is shown a modification in which the upper spring member B of the shell is crimped beneath the lip 24- of the lower shell member A, while member B is under tension, such crimping being shown at (Z, Figure 5. The metal in the shell B above the lip 2 is formed preferably into a groovelike configuration shown 6, thus assisting the turned-under end 25 constantly to exert a pressure beneath such lip.

It will be evident from the foregoing that various changes may be made in the forms shown without departing from the spirit of the invention or the scope of the appended claims.

lVhat I claim is:

1. In spark plug, a body of insulating material, a shell receiving same, said body and shell having cooperating shoulders, and said shell comprising a circumferentially extending first member of spring material and The parts being new rotated by a second member having means thereon for engaging said first member, said first member having a circumferential deformation above said engaging means to place said members under tension and to cause them to bind upon the shoulders of said body.

2. In a spark plug, a body of insulating material, a shell receiving same, said body and shell having cooperating shoulders, and said shell comprising a circumi crentially extending first member of spring material having a portion extending upwardly above the upper shoulder of said body and downwardly againstsaid shoulder thereof, and a second shell member having means thereon for engaging said first member, said first member being cireumferentially deformed to place said members under tension.

3. in a spark plug, a body of insulating material, a shell receiving same, said body and shell having cooperating shoulders, said shell comprising a first member of spring material and a second member having means thereon for engaging said first member, said members being joined together under tension whereby said members bind upon the shoulders of said body, said first member having a portion extending above the upper shoulder of said body and being formed with an annular convolution intermediate said upwardly extending portion and said engaging means on said second member.

i. In a spark plug, a body of insulating material, a shell receiving same. said body and shell having cooperating shoulders, and said shell comprising a first member of spring material and a second member having means thereon tor engaging said first member, said members being joined together under ten sion whereby said members bind upon the shoulders of said body, said first member extending above the upper shoulder or said body and formed with an annular convolution whereby to assist the spring action of said member and said second shell member having an annular upstanding portion enclosing said body in and extending above said engaging means.

In testimony whereof I have affixed my signature to this specification.

HERMAN SCHLAICH. 

